Exercise 1 Page 167

Examining the figure, we see that x^(∘) and 61^(∘) are vertical angles. Therefore, by the Vertical Angles Congruence Theorem, we know that these angles are congruent. x=61 To find y, we can either use the fact that x^(∘) and y^(∘) are alternate exterior angles or we can use that 61^(∘) and y^(∘) are corresponding angles. If we use that 61^(∘) and y^(∘) are corresponding angles, we know by the Corresponding Angles Theorem that they are congruent. y=61